1. Field of the Invention
The present invention relates to an entry apparatus of a memory, and more specifically relates to such an apparatus adapted for easy entry of a digital value in a memory.
2. Description of the Prior Art
As electronic equipment capable of handling the data in a digital form developed, various data handled in an analog value form in the past has been recently handled more in a digital value form than before. A major reason is that once an analog value is converted into a digital value, the data processing of a digital value is extremely easy as compared with the analog value data processing, while the digital value data processing is of high accuracy as compared with the analog value data processing. In addition, the recent development of digital integrated circuits made inexpensive the cost of manufacture of various digital electronic equipment. For these reasons, in many applications conventional analog electronic equipment has been replaced by digital electronic equipment.
In using such digital electronic equipment, it is frequently required that various values are entered or set in a digital value form or are preset by way of initial setting. Such applications that require entry or presetting of a digital value in digital electronic equipment comprise, for example, a radio receiver which can be directly set with digital value data concerning the frequency to be received, a television receiver which can store digital data values concerning the tuning frequency of each channel, an automatic weighing apparatus which is adapted to preset various unit prices, an automatic vending machine which is adapted to process preset prices of various commodities, and the like.
Typically, such digital values are loaded or preloaded in a digital memory such as a core memory, a semiconductor memory, or the like in such digital electronic equipment. Various methods for loading the data or digital values in such a digital memory have also been proposed. Typical methods are described as follows.
(1) A digital switch type
This type comprises a number of digital switches each allotted for each digit of the digital data, such that each digital switch can be set to a desired value in the corresponding digit. According to this type, the larger the number of digits of the data, the greater the number of digital switches to be operated, resulting in tiresomeness in setting the data. Another disadvantage encountered in this type is that the setting of the data is very difficult where the numerical value of the data to be set is not known, such as in case where the frequency of the radio broadcasting is not known.
(2) A ten key type
This type employs a set of ten keys adapted for entry of the numerals 0 through 9. Although this type is advantageous in case where the specific numerical value of the data is known, it is inconvenient in the case where the numerical value of the data is not known, as discussed supra.
(3) An up/down counter type
This type employs an up/down counter operable in response to clock pulses, the count output of which is utilized as the numerical value of the data to be set. Since such a count output is sequentially changeable, the same can be advantageously utilized in setting a numerical value which is unknown to the operator. Assuming, for example, a case where a numerical value associated with the broadcastig frequency is to be set in a radio receiver of a frequency synthesizer type, such as the numerical value "851" corresponding to the broadcasting frequency 85.1 MHz, a counter adapted to be operable responsive to the clock pulses makes use of the count output and, when the numerical value 851 is reached in the counter, the broadcasting frequency is received and a reproduced sound is heard. Thereafter application of the clock pulses to the counter is locked in to set the numerical value 851 in a memory to continually supply the numerical value to the frequency synthesizer. According to this system, however, two types of manual operations are required for up and down counting operations, while a substantial time period is required to cycle throughout a given range of the numerical value to be obtained from the counter. In order to avoid such a problem, preferably two types of operations, quick and slow rates of the change are preferably accommodated by changing the repetition frequency rate of the clock pulses. However, this type of operation results in poor operational performance.